Speed Stability

After reading these posts the last few days, it got me curious to see how stable my Sota turntable speed is based on listening tests and using the strobe disc. I have a stereo test record so I put that on the platter and then my Sota strobe disk which I clamped down onto the record. I have a 4 inch plug-in fluorescent light that makes a good source for the strobe disc. First, I started the turntable with the tonearm up. I locked in on one rectangle on the strobe disc and noted that it stayed in place for several record rotations. Rock steady stable. Next, I cued the tonearm on the outside lead-in groove of my test record and then locked onto a rectangle again on my strobe disc. As the tonearm dropped onto the record I saw no drift of the strobe disc rectangle. Still rock solid steady. I then played the pure test tones on my test record, 440Hz, 1000Hz and 3150Hz- specifically for flutter measurements. To me and my son, these tones were all steady in pitch. But what we both heard was a periodic shift in the image from center to slightly right. So I go to the turntable and get down eye level with the tonearm and I see the tonearm swaying from left to right. Conclusion: My test record has runout. The hole is slightly off center. I see this same issue on several of my records. So my question is: If the source material has some amount of runout, at what point does spending kilo-dollars for better speed stability yield little to no results? Based on my observations and measurements of my Sota here, what am I missing/overlooking?

Tony,

I believe what you may be missing is the sad fact that it may be impossible to fix everything, but all the little things add up, so we try to fix what we can. Look at a turntable the same way you look at an entire system. It will never be perfect, but nothing is left to chance that can be corrected with what is available to its builder.

If one thing is left wrong about a system, or a turntable, in a glaring way, the entire exercise is moot. Suppose someone built an absolutely perfect turntable, but it ran at only 23RPM. That would be obviously wrong. But, suppose someone built a turntable that ran one-tenth of one percent wrong. Would that be acceptable? Maybe, but would it be better, if the guy fixed the tenth of one percent error? Of course, it would. The question is how much can be left wrong, and to what degree.

Now, consider what happens when one thing is fixed that somehow manages to upset some other parameter, and you have the puzzle that turntable designers try to solve. It isn't easy, so they work within the constraints of what they know and can discover. They build with what they can manage to master, and with the help of their smartest friends.

At the end of the day, the hope is that their vision is realized, and that someone out there shares that vision.

Speed stability is one step along that unending path. There are plenty of others, yet to be mastered.

.

I want to think that some labels did a better job of centering the hole in albums than others. I am almost curious enough (but not quite) to measure the hole position of a group of records to see just how far off they are and how much they vary. Maybe someone has already done that- perhaps even by label so we could all know which ones are better for critical listening.

Nakamichi built a couple of very complex turntables (TX-1000 and Dragon} back in the early 80's that centered the record to correct for off-center spindle holes.

I noticed while playing records over the past week that the European and Asian pressings seem to be punched true-ie. no visible swaying of my tonearm. US pressings however, seem to be a mixed bag. Some records are true and some I see the tonearm swaying quite a bit. Still, with the exception of the pure test tone section of my test record, I cannot hear the runout in the music.